Spherical doublet antenna with transmission line feed at current nodal points



G. lNDUNl Feb. 28, 1%67 SPHERICALDOUBLET ANTENNA WITH TRANSMISSION LINE FEED AT CURRENT NODAL POINTS 2 Sheets-Sheet 1 Filed Feb. 20, 1964 INVENTOR. y/a/n/v/v/fA/ uw/ Feb. 28, 1967 G. lNDUNl SFHERICAL DOUBLET ANTENNA WITH TRANSMISSION LINE FEED AT CURRENT NODAL ,POINTS 2 Sheets-Sheet 2 Filed Feb. 20, 1964 INVENTOR. QV I AAW/Zh/DU/V/ ATTOR NE Y United States Patent 3,307,108 SPHERICAL DOUBLET ANTENNA WITH TRANS- MISSION LINE FEED AT CURRENT NODAL POINTS Giovanni Induni, Nusshaumen, Aargau, Switzerland, assignor to Patelhold Patentverwertungs- & Elektro- Holding A.G., Glarus, Switzerland Filed Feb. 20, 1964, Ser. No. 346,154 Claims priority, application Switzerland, May 23, 1960, 5,903/ 60 12 Claims. (Cl. 325119) This application is a continuation-in-part of my copending application Serial No. 112,108, filed May 23, 1961, entitled High Frequency Radiating System and now abandoned.

The present invention relates to radio or high-frequency radiating systems of the type comprising an antenna or radiator connected to a high-frequency apparatus, such as a transmitter or receiver circuit, to provide a connecting or coupling link between said circuit and free or open space as a transmitting medium for high-frequency radiant energy.

Among the objects of the invention is the provision of an improved combination of a high-frequency transmitter and/or receiver and an antenna or radiator which is both compact as well as simple in design and construction; which is substantially free from projecting or obstructing parts; by which the difiiculties and problems of avoiding undesirable radiation from parts other than the effective radiating surface of the antenna proper are substantially eliminated; which may be readily adapted for simultaneous transmission and/or reception of different operating signals; and which is especially suited as a transducer or modulator for radio telemetering small variations in distance or mechanical displacement directly or being derived from other variable magnitudes to be transmitted.

The invention, both as to the foregoing and ancillary objects as well as novel aspects thereof, will be better understood from the following detailed description taken in conjunction with the accompanying drawings, forming part of this specification and wherein:

FIG. 1 is a diagrammatic representation of a high-frequency radiator constructed in accordance with the principles of the invention;

FIG. 1A shows the polar radiation diagram of the radiator of FIG. 1;

FIG. 2 is a view similar to and showing an improvement of the radiator according to FIG. 1;

FIG. 3 is a wiring diagram of a modulated radio transmitter embodying a radiator according to FIG. 2;

FIG. 4 is a partial view showing a further improvement of the radiator according to the invention;

FIG. 5 is a schematic three-dimensional view of another modification of a radiator according to the invention, designed for multiple signal transmission and/or reception; and

FIG. 6 is a view similar to FIG. 1 and showing still another modification of the invention.

Like reference characters denote like parts in the dif ferent views of the drawings.

With the foregoing objects in view, the invention involves generally the provision of a closed hollow space radiator or antenna consisting of conducting material, such as a split spherical doublet or the like symmetrical radiator, said radiator substantially enclosing or housing the transmitting or receiving circuit or apparatus. There are further provided suitable transmission or feeding lines connecting said circuit to predetermined spaced and preferably symmetrical feeding points of the radiator doublet elements, in such a manner as to cause the latter to emit receive high-frequency radiant energy having an operat- 3,307,108 Patented F eb. 28, 1967 ICC ing frequency equal to or differing from the natural or resonating frequency of said radiator. More particularly, in order to afford an energy transmission or coupling between said lines and the feeding points of said radiator, and to effect radiation of high frequency energy into and reception from the surrounding free space, the tuning or effective elecrical length of said lines is so designed and/ or controlled as to cause said feeding points to substantially coincide with current nodal points of said lines, in a manner as will become further apparent as the description proceeds.

The natural or resonating frequency of the hollow space radiator, forming a substantially closed radiating surface, is preferably equal to the operating frequency of the energy being transmitted or received. Advantageously, the radiator may consist of a split hollow sphere provided with an endless slot coinciding with a symmetry plane thereof and being at right angle to the plane including the energy feeding points connected to the transmitting or receiving apparatus, respectively. Alternatively, the transmitting or receiving frequency may be different from the natural frequency of the radiator, as will become further apparent from the following description. Moreover, the radiator may be split in a multiple fashion for simultaneous operation with a plurality of transmitting and/or receiving circuits, which may have different operating frequencies, according to a further feature of improvement of the invention as described in greater detail hereafter.

Referring more particularly to FIG. 1, there is shown schematically and by way of example a sectional view of a high-frequency radiator or apparatus according to the invention, comprising a hollow doublet spherical antenna or space radiator 10 having a pair of semi-circular sections 10a and 10b and completely enclosing or housing a high frequency transmitter or receiver 11. The terminals 12a and 12b of the apparatus or circuit 11 are connected through feeder lines 13a and 13b to points A and B suitably positioned at the symmetry points A and B on the inside surface of the radiator sections 10a and 10b, respectively. In accordance with the present invention, in order to afford eflicient radiation or reception of high frequency radiant energy by the sphere or radiator 10, the tuning or effective electrical length of the feeders 13a and 13b is so designed and/or adjusted as to cause the feeding points A and B to substantially coincide with current nodal points or points of maximum voltage upon said lines during the passage of high frequency energy between the circuit 11 and radiator 10.

Furthermore, the sphere or radiator 10 may be so designed to have a natural resonating frequency determined in a known manner by its mechanical dimensions, which substantially equals the operating frequency of the transmitter or receiver 11. In such a case, the feeding points A and B, which may be regarded as the poles of the sphere, are excited at maximum voltage or caused to coincide with current nodal points upon the feeders 13a and 13b, while the current at the center or equator C-C of the sphere will be at a maximum and the voltage thereat at zero or at a minimum.

In order to ensure an optimum current and voltage distribution as described and, in turn, a maximum radiation efficiency of the system, means may be provided for tuning or adjusting the effective electrical length of the feeders 13a and 13b. This may be accomplished in a known manner by the aid of variable series capacitors and/or inductors or the like tuning impedances inserted in the lines or being structurally embodied in the receiving or transmitting apparatus or circuit 11.

On account of the resultant current and voltage distribution upon the surface of the sphere 10 as described, the latter acts 'as a radiator or collector of radiant energy in cooperation with the transmitter or receiver 11, in the manner of an ordinary open or free space radiator or doublet antenna well known in the art.

In the example illustrated, the tuning means for the feeders 13a and 13b consist of means for varying the effective electrical length of the feeders and are shown in the form of a variable inductor 17 and a variable capacitor 15, inserted in the lines 1312 and 13a, respectively. The tuning means may be adjustable from the outside of the radiator through a pair of operating shafts 15' annd 17' and control knobs 18 and 20, respectively. Furthermore, in FIG. 1 the feeders 13a and 13b are shown to be coupled inductively with the high-frequency apparatus 11 through a coupling transformer comprising a primary winding 16 and the inductance 17 as a secondary or output winding.

As will be understood, the invention is not limited to a spherical radiator as shown by the drawings, but will apply generally to any split and substantially closed or hollow radiating body of conducting material which may have a more or less symmetrical shape in respect to at least one or a plurality of symmetry planes. For practical purposes, it is advantageous to utilize a symmetrical split spherical radiator as shown by the drawing with the connecting points of the feeders from the high-frequency apparatus being located at diametrical symmetry points of the radiating surface, to simplify the construction and adjustment of the feeders, in the manner pointed out, in the interest of ensuring maximum radiation efficiency of the system in a most simple and economical manner.

In using a split radiator as described, the operating frequency may be different from the natural or resonating frequency of the radiator in that the two separately excited parts a and 10b of the radiator are separated into two electrically isolated hemispherical or the like sections by the circumferential slot 21 being at right angle to the line connecting the feeding points A and B, or coinciding with the equator CC of the sphere in the example illustrated. The slot 21 may be open or in the form of an insulating airgap as shown in the drawing or, alternatively, may contain an insulating spacer separating and supporting the two halves 10a and 10b of the sphere 10. In such a case, the demands on the electrical insulating resistance against high voltage stress and. other high-frequency properties of the insulating material used as a spacer or separator are minimized by reason of the fact that the feeding points A and B coincide with current nodal points and, as a consequence, a voltage nodal point or minimum exists in the neighborhood of the slot 21, as pointed out hereinabove. For practical reasons, the width of the slot is made relatively small, that is, compared with the linear dimensions of the radiating body 10.

FIG. 1A shows the polar radiation diagram of a spherical doublet radiator according to FIG. 1, comprising four quadrantial lobes a which are symmetrical to both axes A-B and C-C.

According to a modification of the invention, the two radiating parts or doublet sections 10a and 10b of the radiator 10 may be relatively adjustableto effect modulation of the high frequency energy being transmitted. As arrangement of this type being schematically shown in FIG. 2 may comprise a pair of insulating arms or brackets 22 extending from the sections 10a and 10b and being connected by tensison or compression springs 21' or the like. In an arrangement of this type, a control or variation of the width of the slot 21 by any suitable control force counteracting the force of the springs 21 may be utilized to control or modulate the high-frequency energy produced by the apparatus 11 and radiated by the antenna or radiator 10. Such a device may serve as a radio transducer for telemetering of small variable distances or mechanical displacements either directly or upon conversion from other variable magnitudes to be transmitted.

As an example, the adjustable construction of the radiator sections 10a and 10b according to FIG. 3 may serve for the telemetering by radio of high or extra high tensions or potentials by electrically connecting both sections to a high voltage carrying part, such as a transmission line or the like. As a consequence, the distance of the slot 21 between the parts 10a and 10b, one of which may be stationary and the other may be variable, will be controlled by electrostatic repulsion of the parts in proportion to the voltage or potential to be determined. In this manner, varying 'high or extra high voltages or potential in respect to ground may be transmitted through space to a desired receiving or checking point being at ground potential for indicating, monitoring or control purposes. The high frequency oscillations being generated by the ap paratus mounted within the radiator 10 and emitted by the latter may be modulated in frequency and/or amplitude in accordance with the variable distance between the parts 10a and 10b and may be received and detected by means of any suitable receiving device or circuit known in the art. If desirable, suitable reflecting means may be provided in cooperation with the radiator according to the invention, to modify the radiation characteristic, FIG. 1A, or to cause the radiated energy to be concentrated in a preferred direction for directional or beam transmission, in a manner readily understood by. those skilled in the art.

In the example shown, the oscillations produced by the transmitter 11 are frequency-modulated by the variable capacitor 23 which may be in the form of a condenser microphone or the like transducer and forms an effective element of the transmitter tank or oscillating circuit. In the example shown, the capacitor 23 is operably connected With the doublet elements 10a and 10b through suitable coupling means, as indicated by the dot-dash lines 24 in the drawing.

In the same manner, other variable magnitudes may be transmitted by radio after conversion into proportional variations of the distance between the sections 10a and 10b of the radiator by suitable electrical and/ or mechanical transducing means. In order to increase the mutual capacitance between the sections 10a and 1%, the slot 21 may be reinforced as shown at 24 in FIG. 4. In this manner, the displacement current through the slot may be controlled to suit existing conditions and operating requirements.

Instead of frequency modulating the emitted radiations, transmission may be by means of amplitude modulation by the provision of a suitable modulating device controlled by the sections 10a and 10b in a manner readily understood.

FIG. 3 shows, by way of'example, a simplified wiring diagram for a frequency modulated transmitter of the type according to FIG. 2. The numeral 40 denotes a high frequency oscillator tube, and 41 is an oscillating tank circuit in regenerative circuit connection with said tube, to produce high frequency oscillations which are impressed upon the radiator elements 10a and 101) by means of a coupling coil 42. The capacitor effecting the frequency modulation being shunted across the circuit 41 is comprised, in the example shown, of two capacitor units connected in series and constituted by a first floating electrode 43 operably connected with the section 10a and a pair of cooperating electrodes 44 and 44 operably connected with the section 10b through suitable coupling means (not shown). For identification purposes, the transmitted oscillations are advantageously additionally amplitude modulated in accordance with a lower (audible) signal by the provision of an audio frequency oscillator comprising the tube 45, tank circuit 46 and feedback coil and arranged to modulate the high frequency oscillator by anode modulation, or in any other known manner. If the device is used for high tension telemetering by varying the capacitors 43, 44, 44' and, in turn, the frequency of the transmitted oscillations by the sections 10a and 10b forming anelectrostatic electrometer, the discriminator at the receiving point may be directlycalibrated in high voltage or equivalent units, if the device is used for radio telemetering of a different signal or magnitude.

FIG. 5 illustrates an embodiment of the invention for multiple transmission and/or reception, comprising a pair of high frequency apparatus 11a and 11b enclosed in a common spherical or the like hollow radiator 10, said radiator, in the example shown, being subdivided into four isolated sections or quadrants 25, 26, 27 and 28 by the provision of two circumferential slots 21a and 21b coinciding with a first (horizontal) and a second (vertical) symmetry plane of the sphere 10, respectively. The apparatus 11a is connected to the pairs of quadrants 25, 26 and 27, 28 through feeders 30a and 30b and the apparatus 11b is connected to the pairs of quadrants 25, 27 and 26, 28 through feeders 31a and 31b, respectively, said feeders terminating at points A'-A", B'-B", C-C" and D'D" adjacent to and located on opposite sides of theslots 21a and 21b, as shown in the drawing. In order to prevent mutual interference between the separate transmitters or receivers and radiators thus provided, that is, the component radiators 25, 26-27, 28 cooperating with the circuit 11a and 25, 27-26, 28 cooperating with the circuit 11b, there are provided decoupling inductors 33, 34, 35 and 36 connecting the feeding points A'A", 'B-B", CC" and D'D", respectively, with the ends of the feeders 30a and 30b being connected to the center points of said inductors. As a consequence, in considering, for instance, the quadrants 25 and 26 and associated feeder 30a, transmission of high frequency energy between the quadrants 25 and 26 and originating from the apparatus 11b is blocked by the impedance of the inductor 33, while high frequency energy is permitted to pass freely between the feeder 30a and said quadrants due to the magnetic fields through both halves of the inductor 33 neutralizing one another as a result of the currents therethrough flowing in the opposite direction. The same applies to the remaining decoupling inductors 34, 35 and 36, whereby to enable a simultaneous operation of the circuits 11a and 11b, which may be transmitters and/or receivers of different operating frequencies, in conjunction with the coordinated component radiators 25, 26-27, 28 and 25, 27-26, 28, respectively.

According to a further feature of the invention as shown by FIG. 6, a portion of the hollow radiator enclosing the high-frequency operating circuit may be designed as a substantially plane or counterpoise surface, being constituted for instance, by the metallic surface of a vehicle or the like in the case of a movable radio transmitter and/or receiver. Thus, in FIG. 6, the numeral represents the hollow radiator shown in the form of a hemisphere separated from a plane metallic surface or counterpoise plate 37 by an insulating slot 38. Otherwise, the construction and operation of this modification of the invention is substantially analogous to the previously described embodiment.

According to a simplified embodiment of the inven tion, the operating circuit or device in FIGS. 1 to 3 may be positioned in the center of the hollow sphere or radiator 10 and the length of the feeders 13a and 13b may be equal to one half of the operating wave length, whereby to result in a current node or voltage maximum at the feeding points A and B. If necessary, the lines 13a and 13b may be bent or curved to accommodate the required length in the space enclosed by the radiator, and/ or additional tuning means may be provided in the manner shown, to suit any conditions or requirements.

In the foregoing the invention has been described with reference to a specific illustrative device. It will be evident, however, that variations and modifications, as well as the substitution of equivalent parts or elements for those shown herein for illustration, may be made in accordance with the broader scope and spirit of the invention as set forth in the appended claims. The specification and drawings are accordingly to be regarded in an illustrative rather than in a restrictive sense.

I claim:

1. In a radio system, a high-frequency apparatus, a substantially closed hollow member consisting of electrically conducting material and being symmetrical in respect to at least one symmetry plane, said member arranged to enclose said apparatus on substantially all sides and being provided with an endless insulating gap coinciding with said plane, to provide a pair of separate radiating sections forming a doublet antenna, and a pair of feeding lines connectingsaid apparatus to central feeding points upon said sections on the opposite sides of said plane, said lines having an effective electrical length such as to cause said feeding points to substantially coincide with current nodal points on said lines during transmission of high-frequency energy between said apparatus and said antenna.

2. In a radio system as claimed in claim 1, means reinforcing the edges of said gaps, to increase the electrical capacitance therebetween.

3. In a radio system as claimed in claim 1, said apparatus being a transmitter-oscillator, resilient means insulatingly and yieldingly connecting said sections, and means to modulate said oscillator in accordance with the variations of said gap.

4. In a radio system, a first and a second high-frequency apparatus each having a pair of terminals, a closed hollow member of electrically conducting material and being symmetrical in respect to at least a first and a second symmetry plane at right angles to one another, said member arranged to enclose both said apparatus and being provided with first and second endless insulating gaps coinciding, respectively, with said first and second symmetry planes, whereby to subdivide said member into four separate radiating sections forming a pair of crossed doublet antennae, a first pair of feeding lines connecting one terminal of said first apparatus to adjoining feeding points of both radiating sections on one side of said first symmetry plane and connecting the other terminal of said first apparatus to adjoining feeding points of both radiating sections on the other side of said first symmetry plane, and a second pair of feeding lines connecting one terminal of said second apparatus to adjoining feeding points of both radiating sections on one side of said second symmetry plane and connecting the other terminal of said second apparatus to adjoining feeding points of both radiating sections on the other side of said second symmetry plane, said feeding lines having an effective electrical length such as to cause the respective adjoining feeding points to substantially coincide with current nodal points on said lines during transmission of high-frequency energy between said apparatus and said antennae.

5. In a radio system as claimed in claim 4, including a plurality of inductors interposed between each of said adjoining feeding points and the associated feeding lines, said inductors having their opposite ends connected to said points and having their center points connected to the associated feeding lines.

6. In a radio system, a split-hollow spherical member of electrically conducting material provided with a closed insulating slot coinciding with a symmetry plane thereof, to provide a pair of separate hemispherical radiating sections forming a spherical doublet antenna, a high-frequency apparatus mounted within said radiator to be substantially enclosed thereby, and a pair of feeding lines connecting said apparatus to central feeding points of said sections on the opposite sides of said plane, said lines having an effective electrical length such as to cause said feeding points to substantially coincide with current nodal points upon said lines during transmission of high-frequency energy between said apparatus and said antenna.

7. In a radio system, a first and a second high-frequency apparatus each having a pair of terminals, a hollow spherical member of electrically conducting material en' closing both said apparatus on substantially all sides and being provided with a first and a second endless circumferential insulating gaps coinciding respectively With a first and second symmetry plane of said radiator at right angles to one another, to provide four separate quadrantal radiating sections forming a pair of crossed spherical doublet antennae, a first pair of feeding lines connecting one terminal of said first apparatus to adjoining feeding points of both radiating sections on one side of said first symmetry plane and connecting the other terminal of said first apparatus to adjoining feedings points of both radiating sections on the other side of said first symmetry plane, and a second pair of feeding lines connecting one terminal of said second apparatus to adjoining feeding points of both radiating sections on one side of said second symmetry plane and connecting the other terminal of said second apparatus to adjoining feeding points of both radiating sections on the other side of said second symmetry plane, said feeding lines having an effective electrical length such as to cause the respective feeding points to substantially coincide with current nodal points upon said lines during transmission of high-frequency energy between said apparatus and said antennae.

8. In a radio transmitter, a source of high-frequency energy, a single substantially closed hollow member of electrically conducting material enclosing said source on substantially all sides and having an endless circumferential insulating gap, to provide a pair of separate radiating sections forming a doublet antenna, a pair of feeding lines connecting said source with said sections at central feeding points upon said sections on the opposite sides of said gap, said lines having an effective electrical length such as to cause said feeding points to substantially coincide with current nodal points of said lines, and means to modulate said source in accordance with the variations of said gap.

9. In a radio transmitter as claimed in claim 8, said 8 last means including resilient means insulatingly connecting said sections.

10. In a radio transmitter as claimed in claim 8, including tuning means to adjust the current distribution along said lines.

11. In a radio transmitter as claimed in claim 8, including means to frequency modulate said source in accordance with the Width of said gap and to amplitude modulate the same according to an identifying audio signal.

12. In a radio system, a high-frequency apparatus, a two-part enclosure of electrically conducting material forming a doublet antenna and surrounding said apparatus on all sides, one part of said enclosure constituting a first three-dimensional section and the remaining part forming a second substantially planar section separated from said first section by an intervening endless insulating gap, and a pair of energy feeding lines connecting said apparatus to central points of said first and second sections, respectively, said lines having an effective electrical length such as to cause said feeding points to coincide with current nodal points upon said lines during transmission of high-frequency energy between said apparatus and said antenna.

References Cited by the Examiner UNITED STATES PATENTS 2,256,323 9/1941 Morawetz 325357 X 2,311,491 2/1943 Turner 325-182 X 2,372,228 3/ 1945 Schelkunoff 343898 X 2,520,987 9/1950 Williams et al. 343712 2,618,747 11/1952 Luck 343708 2,686,873 7/1954 Vilkomerson 343795 2,823,365 2/1958 Rines 332-2 X 2,828,413 3/1958 Bowers 325-361 X DAVID G. REDINBAUGH, Primary Examiner.

B. V. SAFOUREK, Assistant Examiner. 

1. IN A RADIO SYSTEM, A HIGH-FREQUENCY APPARATUS, A SUBSTANTIALLY CLOSED HOLLOW MEMBER CONSISTING OF ELECTRICALLY CONDUCTING MATERIAL AND BEING SYMMETRICAL IN RESPECT TO AT LEAST ONE SYMMETRY PLANE, SAID MEMBER ARRANGED TO ENCLOSE SAID APPARATUS ON SUBSTANTIALLY ALL SIDES AND BEING PROVIDED WITH AN ENDLESS INSULATING GAP COINCIDING WITH SAID PLANE, TO PROVIDE A PAIR OF SEPARATE RADIATING SECTIONS FORMING A DOUBLET ANTENNA, AND A PAIR OF FEEDING LINES CONNECTING SAID APPARATUS TO CENTRAL FEEDING POINTS UPON SAID SECTIONS ON THE OPPOSITE SIDES OF SAID PLANE, SAID LINES HAVING AN EFFECTIVE ELECTRICAL LENGTH SUCH 